🔍 Key Concepts

• Jack-up rig leg reaction limits and how environmental loads (waves, wind, current) combine • How maximum allowable wave height is determined from a limiting leg reaction value • Relationship between water depth, wave height, and base shear on a mobile offshore drilling unit (MODU)

💭 Think About

• Which of the given wave heights would most likely produce leg reactions at or just below 5,760 kips, given 70‑knot winds and 2‑knot current already consuming part of the capacity? • How does increasing wave height from 15 ft up to 30 ft affect horizontal loads on the legs—linearly, or more sharply? • In typical jack‑up design practice, is the operational drilling sea state usually closer to smaller, moderate, or very large storm waves?

✅ Before You Answer

• Identify that 5,760 kips is the maximum permissible leg reaction, so the correct choice must correspond to the largest wave height that does not exceed this limit under the stated wind and current. • Consider that wind (70 knots) and current (2 knots) already use up some of the leg‑reaction capacity, so the wave height you choose cannot be unrealistically large for a drilling condition. • Eliminate any option that would more likely correspond to a survival / storm condition rather than a normal drilling operational limit for a coastal jack‑up in 250 ft of water.